This lens is the more modest cousin of Canon’s L-series version, which includes both image stabilisation (IS) and ultra-low dispersion (ULD) glass.
Canon EF 100mm f/2.8 Macro USM
This lens is the more modest cousin of Canon‘s L-series version, which includes both image stabilisation (IS) and ultra-low dispersion (ULD) glass. It might therefore be expected to deliver a fairly ordinary performance, but that is not the case.
Its resolution does dip at f/4 and goes surprisingly low at f/2.8, but it delivers a resolution of about 0.35 cycles-per-pixel from f/5.6 to f/11 and only just crosses the 0.3 cycles-per-pixel line at f/16. These figures all refer to non-macro object distances; results from an improvised macro-MTF test were weaker but this is so with most macro lenses.
The lens focuses quickly, quietly and ultra-reliably, with virtually no hunting observed. The manual-focus ring, which is very broad, can be used any time in AF mode. The AF/MF slider falls under the left thumb, and a second slider, which sets the focusing range, is slightly further down on the same side of the lens.
As is usually the case for true macro optics, the lens is marked with reproduction ratios as well as the focused distance. Canon has put all of this information inside a single window on the top of the lens barrel, which means that the figures are small but they are still reasonably easy to read at a glance.
Objects can be photographed at a predetermined scale by choosing the MF mode and setting the desired reproduction-ratio in the distance window. The object or the camera is then moved forwards and backwards to achieve sharp focus: a micro-adjustment platform can be a huge bonus here as it is all but impossible to move a tripod-mounted camera by a centimetre or less.
Although this is a fine lens some readers may wonder how it compares with the L-series alternative. Sadly, the latter has not been tested, but given that image stabilisation is likely to be of little value in macro photography it is really only the ultra-low dispersion glass that could have genuine appeal. That being the case, it is worth saying that this ‘modest’ lens is already remarkably free of chromatic aberration.
Large-scale resolution is very good save for a weak result at maximum aperture.